1. Field of the Invention
The present invention relates to a burner and as a method for operating such a burner.
2. Discussion of Background
A burner is known from EP-A1-0, 321,809 which consists of two half hollow partial-conical bodies which lie offset one upon the other. The conical shape of the partial-conical bodies shown in the figure of this patent extends in the flow direction at a certain fixed angle. The offset mentioned of the partial-conical bodies relative to one another creates a tangential inlet slot over the complete length of the burner on each of the two sides of the burner body, the width of the slot corresponding to the particular offset of the centerlines of the partial-conical bodies relative to one another and the combustion air flowing into the internal space of the burner through the slots.
A fuel nozzle is located in the internal space at the beginning of the burner and its fuel injection preferably emerges centrally between the centerlines of the partial-conical bodies offset relative to one another. Further fuel nozzles are provided in the region of the tangential inlet slots. Liquid fuel is preferably introduced through the central fuel nozzle whereas the fuel nozzles in the region of the tangential inlet slots are preferably operated with a gaseous fuel. If such a burner is operated with a medium calorific value gas, which usually contains easily ignited hydrogen, there exists the real danger that this gas and the combustion air introduced will mix so strongly even in the inlet region, at the location where they meet, in such a way that premature ignition of the mixture can occur. This would in turn lead to diffusion-type combustion with greatly increased NO.sub.x emission. In addition, it may also be the case that shear layers can easily occur with such air/gas mixing and the result of this is instability in the mixing process due to strong eddying. If gas supply pressure pulsations occur because of the above-mentioned instability, this additionally leads to strong vibrations in the system.